1. Field of the Invention
The invention relates to thermoelectric refrigerators, and particularly to highly compact portable thermoelectric refrigerators.
2. Description of the Prior Art
Portable ice boxes or coolers have been widely used by motorists, outdoorsmen, etc. despite the fact that portable ice coolers have numerous shortcomings because there have been no viable, commercially feasible alternatives to their use. For example, the ice which must be utilized therein greatly increases the weight, and melts rapidly, sometimes causing perishables stored in the cooler to become waterlogged or otherwise spoiled and frequently is unavailable when and where it is needed. Consequently, several thermoelectric refrigerators, including the one described in the co-pending patent application "CONTROL CIRCUITRY FOR THERMOELECTRIC COOLER", Ser. No. 6/102,447, filed Dec. 11, 1979, by Michael A. Reed, have become increasingly popular. However, the thermoelectric refrigerator described in that patent application, while being very satisfactory for implementation of medium sized and large thermoelectric refrigerators, is less satisfactory for a very small thermoelectric refrigerator. There has been, prior to the present invention, an unmet need for a very small, lightweight, highly compact thermoelectric refrigerator having exterior dimensions of approximately 11 inches by 11 inches by 16 inches, wherein the size of the interior storage compartment is maximized.
Accordingly, it is an object of the invention to provide a lightweight, low cost thermoelectric refrigerator having maximum storage space for a particular set of external dimensions.
Prior thermoelectric refrigerators typically have an internal heat exchanger which either consists of a smooth solid plate across the bottom of the storage compartment, wherein a thermoelectric module contacts the solid plate approximately centrally, or a side mounted finned internal heat exchanger, wherein the thermoelectric module approximately centrally contacts the finned internal heat exchanger. In either case, relatively uniform cold temperatures exist across such internal heat exchangers, resulting in relatively uniform temperatures in the storage compartments of the prior thermoelectric refrigerators, even after thermal equilibrium has been established therein. However, there is frequently a need to store different perishable foods at different temperatures, as some foods need to be kept relatively colder than others. For example, it may be desirable to keep foods such as meats and dairy products approximately 10 degrees colder than certain other foods such as lettuce.
Accordingly, it is an object of the invention to provide a portable thermoelectric refrigerator which provides a predetermined temperature gradient in a single compartment which contains perishable foods or the like.